Copper-base alloy containing titanium and antimony

ABSTRACT

DISCLOSE ARE ALLOY COMPOSITIONS CONSISTING ESSENTIALLY OF COPPER AND SMALL AMOUNT OF TITANIUM AND ANTIMONY WITHIN STATED RANGES. THESE COMPOSITIONS HAVE HIGH ELECTRICAL CONDUCTIVITY, HIGH STRENGTH AND HIGH DUCTILITY AS COMPARED WITH COPPER ALLOYS CONTAINING EITHER TITANIUM OR ANTIMONYL. THE DISCLOSED RANGES OF ALLOY COMPOSITIONS PROVIDE A CLASS OF COPPER-BASE ALLOYS HAVING A UNIQUE FLEXIBILITY WITH REGRAD TO ELECTRICAL, MECHANICAL AND PHYSICAL PROPERTIES. BY VARYING THE RELATIVE AND TOTAL AMOUNTS OF TITANIUM AND ANTIMONY, COPPER-BASE ALLOYS HAVING PREDICATABLE AND DIFFERING PROPERTIES MAY BE OBTAINED. METHODS FOR THE HEAT TREATMENT AND FABRICATION OF THE ALLOYS ARE ALSO DISCLOSED.

N 2- 1974 D. J. NESSLAGE ETAL 3,832,241

COPPER-BASE ALLOY CQNTAINING TITANIUM AND ANTIKONY Original Filed Sept. 25, 1972 We 0 2 o -m 2 2 v n O n O s rm om r t b -b l C" S w .7 0 m .71 C 2. nm%m m T w w H 2 m w mm A O w w. W mus m 4;. 2 0 O( T wT m m. h v m e W O O O O O O O O 0 mm 8 6 4 2 H 9 8 7 w w Figure1 Figure 2 United States Patent 3,832,241 COPPER-BASE ALLOY CONTAINING TITANIUM AND ANTIMONY Donald J. Nesslage, Old Bridge, and Liu S. Yu, Franklin Park, NJ., assignors to Phelps Dodge Industries, Inc., New York, N.Y.

Original application Sept. 25, 1972, Ser. No. 222,186, now Patent No. 3,773,505. Divided and this application Aug. 8, 1973, Ser. No. 386,508

Int. Cl. C22c 9/00; C22f N08 US. Cl. 148--12.7 4 Claims ABSTRACT OF THE DISCLOSURE ods for the heat treatment and fabrication of the alloys are also disclosed.

This is a division of application Ser. No. 292,186, filed Sept. 25, 1972, now US. Pat. 3,773,505.

The invention relates to copper-base alloys that are particularly useful as conductors in applications requiring greater tensile strength or greater ductility at a given tensile strength than possessed by pure copper.

Copper-base alloys, that is, alloys wherein copper is the predominant component, containing both titanium and antimony have not been found in the literature. Copper-titanium alloys and alloys having coppeg and titanium with lead, tin or zinc are known. See US. Pats. Nos. 2,616,800 and 935,863, respectively.

This invention relates to copper-base alloy compositions, and more particularly to copper-base alloy compositions containing small amounts of titanium and antimony within stated ranges.

It is an object of this invention to provide a class of copper base alloy compositions wherein the electrical, mechanical and physical properties of copper may be predictably modified by altering the relative and total concentration of titanium and antimony, the alloying elements.

It is a further object of this invention to provide copper-base alloys possessing high electrical conductivity, high strength and high ductility, as compared with copper-base alloys containing either titanium or antimony.

It is a further object of this invention to provide methods for the heat treatment and fabrication of the copperbase alloys disclosed.

The class of copper-base alloys of the present invention consists essentially of titanium, antimony and a copper base, the titanium being present in an amount from about 0.08 to about 0.7 weight percent and the antimony from about 0.05 to about 1 weight percent.

Pure copper (Copper Development Association Copper No. 102) in spring temper characteristically possesses an IACS (International Annealed Copper Standard) conductivity of 101 percent and a UTS (ultimate tensile strength) of 55,000 p.s.i. with a ductility of four percent elongation in two inches, while certain compositions of the class of copper alloys of this invention possess, when properly processed, electrical conductivities in excess of 85 percent IACS and tensile strengths of over 60,000

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p.s.i. with ductilities greater than 12 percent elongation in two inches. Other compositions possess electrical conductivities in excess of percent IACS and tensile strengths of over 80,000 p.s.i. with ductilities greater than eight percent elongation in two inches.

The alteration in the electrical, mechanical, and physical properties of the copper-base alloys is attained by varying the relative and total amounts of the alloying elements, titanium and antimony. The elfects of these variances are shown in Table I. (The tables herein report only the titanium and antimony content. It should be understood that the balance of the alloy composition is essentially copper. Throughout the specification RT=reduction in thickness, YS=yield strength, and R =Rock- Well B method.)

TABLE I Properties of Cu-Fi-Sb alloys Cold rolled 75% RT, aged at 800 F. for 2 hrs. Cold rolled 60% RT, re-aged at 700 F. for 1 hr.

Tensile properties Composition, Electrical Percent wt. percent conductivity YS at 0.5% elongation (percent UTS extension in 2 Ti Sb AC S) (p.s.i.) (p.s.i.) inches 13 0. 5 73 61, 000 60, 000 9 086 10 89 56, 800 51, 800 13 .12 .13 86 61, 000 15 l2 15 86 13 12 16 86 10 15 86 09 14 89 066 11 89 10 17 87 12 20 84 10 25 82 11 33 74 11 72 57 10 1. 36 39 l6 01 70 15 10 85 l6 17 85 14 19 85 25 26 22 25 80 23 28 79 21 29 80 22 32 81 23 86 80 22 37 76 24 1. 36 43 33 37 71 31 39 75 31 43 75 31 44 76 32 49 76 33 56 76 36 62 69 34 64 69 42 23 45 44 52 67 42 53 68 42 58 75 79, 000 77, 800 15 43 63 74 82, 000 10 41 64 75 000 10 43 72 66 85, 000 83, 500 8 44 1. 35 52 74, 500 68, 400 12 48 10 33 400 72, 200 7 48 56 05 81, 000 78, 900 7 55 62 64 84, 500 800 8 50 64 68 85, 500 000 8 49 67 71 82, 500 80, 300 8 52 76 73 81, 500 79, 800 8 50 80 69 85, 500 84, 200 8 49 82 71 85, 000 83, 500 8 69 1. 06 70 80, 700 78, 000 9 As the data of Table I demonstrate, the electrical conductivity of the copper-base alloys decreases with increasing titanium content, and the ultimate tensile strength increases. The data also illustrate that for any given titanium content, a greater value of electrical conductivity is achieved by maintaining the amount of antimony at 0.3 to 0.8 weight fraction of the total alloying concentration, total alloying concentration being defined as the sum of the antimony and titanium content of the alloy. For example, copper-base alloys containing 0.10 weight percent titanium and 0.17 weight percent antimony or 0.14 weight percent titanium and 0.19 weight percent antimony, yield, respectively, electrical conductivities of 87 percent and 85 percent IACS, while copperbase alloys containing 0.11 weight percent titanium and 0.33 weight percent antimony, or 0.13 weight percent titanium and 0.05 weight percent antimony yield, respectively, electrical conductivities of 74 percent and 73 percent IACS. The preferred antimony range is from about 0.56 to about 0.61 weight fraction of the total alloying concentration.

The foregoing are more clearly illustrated in the figures, wherein:

FIG. 1 shows electrical conductivity as a function of fixed weight percents of titanium and the relative antimony content of the total alloying concentration; and

FIG. 2 shows ultimate tensile strength as a function of the total alloying concentration.

In the drawings, FIG. 1 is a graph which shows the relationship of the electrical conductivity of the copperbase alloy to its titanium and relative antimony content when the alloy is processed in a preferable manner. Each curve represents the effect of antimony concentration on the conductivity of a copper-base alloy with a given titanium content. It may be seen that although the titanium content produces a pronounced effect on the electrical conductivities of this alloy, the relative antimony content also exerts an important influence. In particular, increased electrical conductivity is observed with an antimony content between 0.3 and 0.8 weight fraction of the total alloying concentration, with the preferred range of antimony content being from about 0.56 to about 0.61 weight fraction.

FIG. 2 is a graph which represents the effect of total alloy content on the ultimate tensile strength of the copper-base alloy disclosed, when the alloy is processed in a preferable manner. It may be seen that additions of titanium and antimony, in the preferred relative proportions disclosed above, markedly increase the ultimate tensile strength of the copper-base alloy up to a total alloy content of about one weight percent. Beyond this, the gain in ultimate tensile strength with increased alloy additions is somewhat less significant.

The effects of alloying titanium and antimony with copper as disclosed are such that alloy composition ranges may be chosen from within the overall composition range disclosed in order to provide alloys with properties optimally balanced as desired. As is evident from Table I, relatively high electrical conductivity, and a high tensile strength with improved ductility, are available where the titanium content is from about 0.1 weight percent to about 0.2 weight percent, if greater emphasis on the electrical conductivity is desired, and from about 0.3 weight percent to about 0.4 weight percent if greater emphasis on tensile strength is chosen.

Throughout the specification, the values given for electrical, mechanical or physical parameters are those found for the indicated composition after the alloy has been processed according to one of the procedures set forth hereafter.

The following examples will serve to illustrate the nature of some of the available optimizations disclosed.

EXAMPLE I If an alloy of relatively high electrical conductivity with improved strength is desired, an alloy containing from about 0.1 to about 0.2 weight percent titanium and from about 0.1 to about 0.4 weight percent antimony might be chosen. Statistical analysis of relevant data disclosed ir 1 Table '1 indicate that an alloy within this ap- 4 proximate compositional range has the properties listed in Table II.

TABLE 11 Properties of copper-base alloy containing 0.10 to 0.23 wt. percent titanium and 0.10 to 0.36 wt. percent antimony Property 99% confidence limits Electrical conductivity 83.5% IACS. 81.3% to 85.6% IACS,

Ultimate tensile strength 67,300 p.s.L- 63,000 to 71,500 p.s.i.

Yield strength at 0.5% ex- 62,700 p.s.l. 57,500 to 67,800 p.s.i.

tension.

Elongation in 2 inches 11.7% 10.1% to 13.2%.

Alloys processed by cold-rolling 75% reduction in thickness from hot-worked condition, heat-treating at 800 F. for 2 hours, cold-rolling another 60% reduction in thickness, and heat-treating at 700 F. for

1 hour.

EXAMPLE II Mean value TABLE III Properties of copper-base alloy containing 0.30 to 0.43 wt. percent titanium and antimony from 0.56 to 0.61 weight fraction of total alloying concentration Property Mean value 99% confidence limits Electrical conductivity 75.2% IACS,".-. 74.0% to 76.4% IAQS.

Ultimate tensile strength..- 80,200 p.s.i 78,200 to 82,100 p.s.r.

Yield strength at 0.5% ex- 78,500 p.s.r- 75,900 to 81,000 p.s.i.

tension.

Elongation in 2 inches 11% 7% to 15%.

Alloys processed by cold-rolling 75% reduction in thickness from hot worked condition, heat-treating at 800 F. for 2 hours, cold-rolling another- 60% reduction in thickness, and heat-treating at 700 F. for 1 hour.

Small amounts of intentionally or unintentionally added impurities, such as those contained in the master alloys or residual deoxidizers, do not significantly change the mechanical and physical properties of the alloys.

In manufacturing the alloys, it is preferred to use oxygen-free copper or electrolytic copper, although other high purity coppers may also be utilized. The alloying ingredient may be in any form suitable for alloying purposes, such as metal sponges, master alloys, and so on. Conventional melting, alloying and casting practices may be utilized. A particularly good practice is to melt the copper in an induction furnace under a charcoal cover of protective atmosphere, or under vacuum.

Deoxidization may be made with a chemical deoxidizer, if so desired, without detrimental eifects on the properties of the alloys, as illustrated in the following Example.

EXAMPLE III In a comparison test, an alloy containing 0.10 weight percent titanium and 0.15 weight percent antimony resulted in an electrical conductivity of 86% IACS, a tensile strength of 62,000 p.s.i., and a ductility of 12.5% elongation in two inches, while another alloy of the same composition but deoxidized with lithium during melting resulted in a conductivity of 86% IACS, a tensile strength of 62,500 p.s.i., and 12% elongation in two inches.

It is preferred to cast the alloys into billets or wire bars of conventional sizes and subject them to hot-working, as by hot-rolling, extrusion, and so forth. Hot-working can be carried out at any elevated temperature below the alloys melting point, with a range of from about 1500 to about 1750" F. being preferred. The alloys should then be cooled rapidly, cold-worked as by cold-rolling or drawing, and heat-treated. Cold-Working and the subsequent heat treatment, henceforth referred to as aging treatment, are necessary to develop the optimum properties.

An alternative is to give the alloys a solution heat treatment at temperatures above 1500 F. after casting, hot-working or cold-working, and then subject them to cold deformation or aging heat treatment, or both. Aging without prior cold work may result in inferior properties, however.

The aging temperature and the time depend on the degree of cold deformation. Generally, smaller amounts of cold work require a higher aging temperature or a longer aging time or both. The ultimate properties will not be the same with different cold work-aging schedules. By way of illustration, the properties of an alloy resulting from different processing schedules are given in the following example.

It is seen that the electrical conductivity and hardness values vary somewhat.

The dependence of properties on cold-working and aging treatments offers an easily accessible means of controlling the properties of the alloys. Example IV also reveals the excellent resistance to annealing characteristics of the copper-base alloys of the present invention.

In general, an initial cold reduction of less than about 85% necessitates further cold-working and aging treatments to yield alloys having optimum properties. Also, for the same total amount of cold reduction two or more cold work-aging cycles generally result in higher electrical conductivity and tensile strength than a single cycle treatment. The effect of cold work and aging cycle treatments on the properties of the alloys are more fully understandable from the following example.

EXAMPLE V TABLE V Composition: 0.33 wt. percent Ti and 0.42 wt. percent Sb cold-rolling) 75 92 87, 000 79, 200

In Examples IV and V the different amounts of cold work and the difierent aging treatments are adopted solely for the purpose of illustration.

The alloys disclosed may be used where some sacrifice in electrical conductivity may be made in exchange for tensile strength or ductility, or both, greater than that of pure copper. Some examples would be their use in switch components, electrical contacts, electrical current-carrying springs, lead frames for semiconductive devices, and high-strength hookup wires and cable.

We claim:

1. A method of heat-treating an alloy consisting essentially of titanium, antimony and a copper base, having an antimony content of from about 0.08 to about 0.7 weight percent and a titanium content of from about 0.05 to about 1 weight percent, wherein the alloy is cooled rapidly after heat-treating or hot-Working, or both, at a temperature above 1500 F. but below its melting point and subsequently heat-treated, with or without intermediate cold-working, at a temperature between 600 and 1000 F.

2. The method of Claim 1 wherein the initial heat-treating or hot-working, or both, is at a temperature between 1500 and 1750 F.

3. A method of fabricating an alloy consisting essentially of titanium, antimony and a copper base, having an antimony content of from about 0.08 to about 0.7 weight percent and a titanium content of from about 0.05 to about 1 weight percent, wherein the alloy is subjected to rapid cooling after heat-treating or hot-working, or both, at a temperature above 1500 F. but below its melting point, reduced in cross-sectional area by any suitabe coldworking means, heat-treated at a temperature between 600 and 1000 F., again reduced in cross-sectional area by any suitable cold-working means and heat-treated again at a temperature between 600 and 1000 F., the above being conducted either with or without subsequent cold-working.

4. The method of Claim 3 wherein the initial heattreating or hot-working, or both, is at a temperature between 1500 and 1750 F.

References Cited UNITED STATES PATENTS 2,030,921 2/1936 Hessenbruch 164 2,069,906 2/1937 Vaders 75-153 X 2,086,604 7/ 1937 Comstock 75164 X 2,797,300 6/ 1957 Hawthorne 75-164 X 2,943,960 7/ 1960 Saarivirta 148--l2.7

FOREIGN PATENTS 1,254,869 11/1967 Germany 75164 CHARLES N. LOVE'LL, Primary Examiner U.S. Cl. 

